I'm trying to find more info on 2gb vs 4gb. What I've actually been finding is that 4gb performance is almost all in people's head, but still not done researching yet...

4gb RAM is much harder to overclock and you can get RAM at higher speeds and lower latency in a 2x1 configuration than 2x2. Check this out which places a 2gb of faster RAM vs 4gb of slightly slower RAM. Even without overclocking, 4gb gets a slightly better max framerate which results in a slightly higher average, but 2gb of faster RAM provides a marginally higher mininmum which will translate to less choppy gameplay which you will notice more than the extra .5 average fps.

4GB RAM much harder to overclock? That a load of nonsense. My friend used 4GB 800MHz DDR2 OCZ Platinum, it very easy to overclock his Q6600 to 3.6GHz through Vista x64 with BIOS settings set to Auto.